1. Field of the Invention
The present invention relates to a reference data generating method for use in making a comparison with sensed data obtained by image-picking up a pattern formed on a photo mask, a semiconductor wafer or the like.
In addition, the present invention relates to a pattern defect checking apparatus and checking method for checking a pattern defect by comparing a sensed data obtained by image-picking up a pattern formed on a photo mask, a semiconductor wafer or the like with a reference data obtained by expanding a design data of the pattern.
Further, the present invention relates to a reference data generating program of generating a reference data for use in pattern defect check by a computer.
Also, the present invention relates to a method of manufacturing a semiconductor device by using a photo mask after checking a pattern defect by comparing a sensed data obtained by image-picking up a pattern formed on a photo mask with a reference data obtained by expanding a design data of the pattern.
2. Description of the Related Art
Conventionally, in the case of carrying out a defect check of a pattern formed on a photo mask for use in manufacturing semiconductor devices, light beams are radiated onto a photo mask from a light beam source such as a mercury lamp or a laser oscillation source. A pattern image data (sensed data) obtained by image-picking up light beams passed through the mask is compared with a reference data obtained by expanding a design data of the pattern, to detect an unmatched portion as a defect. In recent years, a photo mask pattern has been finer, and the size of a defect to be detected has been smaller than 100 nm. In addition, it is necessary to carry out a defect check with high sensitivity for a mask using a high resolution technique such as a phase shift or optical proximity effect correction.
In order to enhance detection sensitivity, it is necessary to enhance alignment between a reference data obtained by expanding a design data of a pattern to be formed on an object and a sensed data obtained by image-picking up a pattern formed on the object. In a conventional reference data generating method, a feature of a pattern targeted to be checked is geometrically calculated, and the calculated pattern feature is optically calculated (for example, Jpn. Pat. Appln. KOKAI Publication No. 2002-107309).
In such a conventional method, however, the calculation result largely depends on a calculation model, and figures smaller than an inspection pixel size may be arbitrarily calculated, and thus the alignment between the reference data and the sensed data is low. In particularly, in the optical proximity effect correction mask, dimensions of an assisting pattern are extremely small to a line width of a main pattern, thus making it difficult to obtain a reference data with high accuracy. In addition, a large amount of time has been required for calculation because geometrical and optical calculations are carried out.
As described above, in a pattern defect check for checking a pattern formed on an object targeted to be checked, it is necessary to provide a reference data from a pattern design data. However, a large amount of time is required to provide a reference data, and it is difficult to provide a reference data with high alignment with a sensed data.